Ordering Recommendation

Preferred genetic test for the detection of variants causing X-linked Alport syndrome.

Mnemonic
ALPORT FGA
Methodology

Polymerase Chain Reaction/ Sequencing/Multiplex Ligation-dependent Probe Amplification

Performed

Varies

Reported

28-35 days

New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.
Specimen Required
Patient Preparation
Collect

Lavender (EDTA), pink (K2EDTA), or yellow (ACD solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 2 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions
Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval
Interpretive Data

Background Information for: Alport Syndrome, X-linked (COL4A5) Sequencing and Deletion/Duplication
Characteristics:
Progressive renal and cochlear disease with 30-40 percent incidence of ocular involvement; 60 percent of males reach end-stage renal disease by age 30, and 85 percent have sensorineural deafness by age 40.
Incidence:
Approximately 1 in 50,000 live births.
Inheritance:
X-linked recessive; de novo mutations in 10-15 percent of affected males.
Penetrance:
Variable, depending on mutation and sex.
Cause:
Pathogenic type 4 collagen alpha chain 5 (COL4A5) mutations.
Clinical Sensitivity:
Greater than 80 percent for X-linked Alport syndrome in males or females.
Methodology:
Bidirectional sequencing of the entire COL4A5 coding region and intron-exon boundaries and multiplex ligation-dependent probe amplification (MLPA) to detect large COL4A5 coding region deletions and duplications.
Analytical Sensitivity & Specificity:
99 percent.
Limitations:
Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations and deep intronic mutations will not be detected. Breakpoints of deletions/duplications will not be determined. Mutations in genes, other than COL4A5, are not evaluated. Deletions/duplications in exons 8, 25, 40, 42, and 43 of the COL4A5 gene will not be detected.

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

81407; 81408

Components
Component Test Code* Component Chart Name LOINC
2002399 ALPORT FGA Specimen 31208-2
2002401 Alport (COL4A5) Seq and Del/Dup Interp 53853-8
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Alport syndrome molecular testing
  • X-linked Alport syndrome molecular testing
Alport Syndrome, X-linked (COL4A5) Sequencing and Deletion/Duplication